1 files changed, 37 insertions, 24 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 91768d5dbfb9..8eb49e055ec0 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -57,6 +57,7 @@ struct vcpu_vmx {
                 u16           fs_sel, gs_sel, ldt_sel;
                 int           gs_ldt_reload_needed;
                 int           fs_reload_needed;
+                int           guest_efer_loaded;
         }host_state;
 
 };
@@ -74,8 +75,6 @@ static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
 static struct page *vmx_io_bitmap_a;
 static struct page *vmx_io_bitmap_b;
 
-#define EFER_SAVE_RESTORE_BITS ((u64)EFER_SCE)
-
 static struct vmcs_config {
         int size;
         int order;
@@ -138,18 +137,6 @@ static void save_msrs(struct kvm_msr_entry *e, int n)
                 rdmsrl(e[i].index, e[i].data);
 }
 
-static inline u64 msr_efer_save_restore_bits(struct kvm_msr_entry msr)
-{
-        return (u64)msr.data & EFER_SAVE_RESTORE_BITS;
-}
-
-static inline int msr_efer_need_save_restore(struct vcpu_vmx *vmx)
-{
-        int efer_offset = vmx->msr_offset_efer;
-        return msr_efer_save_restore_bits(vmx->host_msrs[efer_offset]) !=
-                msr_efer_save_restore_bits(vmx->guest_msrs[efer_offset]);
-}
-
 static inline int is_page_fault(u32 intr_info)
 {
         return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
@@ -351,16 +338,42 @@ static void reload_tss(void)
 
 static void load_transition_efer(struct vcpu_vmx *vmx)
 {
-        u64 trans_efer;
         int efer_offset = vmx->msr_offset_efer;
+        u64 host_efer = vmx->host_msrs[efer_offset].data;
+        u64 guest_efer = vmx->guest_msrs[efer_offset].data;
+        u64 ignore_bits;
+
+        if (efer_offset < 0)
+                return;
+        /*
+         * NX is emulated; LMA and LME handled by hardware; SCE meaninless
+         * outside long mode
+         */
+        ignore_bits = EFER_NX | EFER_SCE;
+#ifdef CONFIG_X86_64
+        ignore_bits |= EFER_LMA | EFER_LME;
+        /* SCE is meaningful only in long mode on Intel */
+        if (guest_efer & EFER_LMA)
+                ignore_bits &= ~(u64)EFER_SCE;
+#endif
+        if ((guest_efer & ~ignore_bits) == (host_efer & ~ignore_bits))
+                return;
 
-        trans_efer = vmx->host_msrs[efer_offset].data;
-        trans_efer &= ~EFER_SAVE_RESTORE_BITS;
-        trans_efer |= msr_efer_save_restore_bits(vmx->guest_msrs[efer_offset]);
-        wrmsrl(MSR_EFER, trans_efer);
+        vmx->host_state.guest_efer_loaded = 1;
+        guest_efer &= ~ignore_bits;
+        guest_efer |= host_efer & ignore_bits;
+        wrmsrl(MSR_EFER, guest_efer);
         vmx->vcpu.stat.efer_reload++;
 }
 
+static void reload_host_efer(struct vcpu_vmx *vmx)
+{
+        if (vmx->host_state.guest_efer_loaded) {
+                vmx->host_state.guest_efer_loaded = 0;
+                load_msrs(vmx->host_msrs + vmx->msr_offset_efer, 1);
+        }
+}
+
 static void vmx_save_host_state(struct kvm_vcpu *vcpu)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -406,8 +419,7 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
         }
 #endif
         load_msrs(vmx->guest_msrs, vmx->save_nmsrs);
-        if (msr_efer_need_save_restore(vmx))
-                load_transition_efer(vmx);
+        load_transition_efer(vmx);
 }
 
 static void vmx_load_host_state(struct vcpu_vmx *vmx)
@@ -436,8 +448,7 @@ static void vmx_load_host_state(struct vcpu_vmx *vmx)
         reload_tss();
         save_msrs(vmx->guest_msrs, vmx->save_nmsrs);
         load_msrs(vmx->host_msrs, vmx->save_nmsrs);
-        if (msr_efer_need_save_restore(vmx))
-                load_msrs(vmx->host_msrs + vmx->msr_offset_efer, 1);
+        reload_host_efer(vmx);
 }
 
 /*
@@ -727,8 +738,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 #ifdef CONFIG_X86_64
         case MSR_EFER:
                 ret = kvm_set_msr_common(vcpu, msr_index, data);
-                if (vmx->host_state.loaded)
+                if (vmx->host_state.loaded) {
+                        reload_host_efer(vmx);
                         load_transition_efer(vmx);
+                }
                 break;
         case MSR_FS_BASE:
                 vmcs_writel(GUEST_FS_BASE, data);